When a fork lift truck is operated in a warehouse with narrow aisles and high shelves it often becomes quite difficult even for experienced operators to accurately align the forks in a vertical direction with the narrow space between a shelf and a pallet bottom into which the forks are to be inserted. Damage to the shelving and to the pallets often results. Inasmuch as fork lift trucks are usually battery-powered and therefore have a convenient source of electrical power readily available, it is desirable to provide simple electronic means to give the operator at least a clear height indication in as large a scale as possible, and preferably to give the operator a way to accurately and automatically stop the forks at a predetermined height.